Seeing even the very few Modders that Civ VI have in account arg if the DLL is THAT crucial for modding, just leaves the impression that the devs might be much less likely of thinking to release the DLL for us.
I used to mod only with the database modifiers and thought that we can make various things with them. Which is true, but with Lots of limitations (and there are not enough IMO). Hence, I started to learn lua in order to overcome the limitations, and guess what? it's even more restricted. We cannot make a lot of things that should be at least possible with lua. Perhaps it is possible, but because of the lack of documentation, it's like groping around in a dark room. With access to more lua objects and a better/reliable interaction between Gameplay and UI Scripts, it would open a lot of possibilities, so that we can make even new considerable mechanisms with them. But how do we gonna make AI make use of those? in a Proper way? Ok, let's just jump back to modifiers, are YOU really happy with the current AI decisions? do you really think the AI is making a good use out of the things added with Mods? Yeah,... exactly. NOPE.
I might be a newbie to the Civ modding community, who doesn't know exactly what can be achieved with access to DLL, but as long as we cannot make AI better with our current possibilities, I won't be satisfied with the Game till we get the DLL. And I'm even willing to learn C++, if the DLL gets out, in order to get rid of the current stupidity of AI (not to mention Diplomacy, Deals, CS, Units management...). I would even pay for it.